Piston



Aug. 20, 1940. BRE-rz 2,212,148

PISTON Original Filed Sept. 9, 1938 2 Sheets-Sheet l In ventor A iiorneys Aug. 20, 1940. s BRETZ 2,212,148

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A iiorneys Patented Aug. 20, 1940 ST'E'ES PISTON John S. Bretz, Detroit, Mich.

Application September 9, 1938, Serial No. 229,200 Renewed February 26, 1940 1 Claim.

This invention relates to pistons, particularly pistons adapted for internal combustion engines and the like.

An object of the present invention is to provide a piston which is expansible in part, the piston in accordance with the present invention having sections automatically. adjustable inwardly and outwardly to maintain true contact with the cylinder wall thereby eliminating piston slap and equalizing the wear on the cylinder wall.

The invention together with its objects and advantages will be best understood from a study of the following description taken in connection with the accompanying drawings wherein:

Figure 1 is a side elevaticnal view of the piston.

Figure 2 is a vertical sectional view therethrough and taken substantially on the line 2-2 of Figure 3.

Figure 3 is a sectional view taken substantially at right angles to Figure 2.

Figure 4 is a top plan View of the piston.

Figure 5 is a top plan view of the piston with the head removed and certain parts shown in section, and

Figure 6 is a detail sectional View taken substantially on the line 6-6 of Figure 1.

Referring to the drawings by reference numerals it will be seen that in the preferred embodiment thereof the improved piston comprises a solid piston head 5 which in its periphery is provided with a groove 6 in which may be fitted a piston ring for effecting a tight contact with the cylinder wall.

Further the piston includes an upper skirt section I and a lower skirt section 8.

The skirt section 8 is provided with an integral head or partition 9, and said skirt section 8 is detachably connected with the head 5 through the medium of a pair of threaded bolts Ill.

The skirt section 8 is provided with wrist pin bosses H for accommodating the wrist pin [2.

The skirt section 1 fits between the head 5 and the lower skirt section 8 and is composed of a pair of complemental half-sections |3I3 out along a plane passed through the longitudinal axis of the piston.

Each of the sections l3 at one edge thereof is provided with a tongue M and at an opposite edge thereof with a groove Hi to receive the tongue M of the other section whereby said sections l3l3 are joined together at diametrically opposite sides of the piston through the medium of a tongue M and a groove it as clearly suggested in Figure 6.

Arranged between the half-sections |3-| 3 of the piston skirt section 1, and through the medium of which said half-sections iii are continuously pressed away from each other toward the walls of the cylinder to insure a proper fit, is an expansion device indicated generally by the reference numeral 16.

The expansion device 16 is in the form of a disk out along a plane passed through the diameter of the disk to provide a pair of complemental sections llll that have rounded outer edges to fit against the inner surfaces of the halfsections |3--l3. At the straight edges thereof the expanding elements i"l--ll are provided with sockets E8 to accommodate the ends of a coil spring it that serves to urge the expanding elements ll away from one another and into contact with the skirt half-sections l3-i3 and the latter into contact with the cylinder wall.

For the expander-elements I? there are provided a pair of guide members 26.

Each guide member 20 is provided intermediate its ends with an opening to accommodate a bolt ID, and the ends of the guide members 20 are accommodated in slots 2 provided therefor in the expander-elements |l'll as will be clear from a study of Figure 3.

The guide members 20 are secured on the bolts ID at the desired position of adjustment on said bolts through the medium of pair of jamb nuts, each pair of jamb nuts including a jamb nut 23 and a jamb nut 24 as also shown best in Figure 3.

From the above description it will be noted that but a single piston ring of conventional form may be used, the latter being accommodated in the groove 6 provided therefor in the piston head 5. It will also be appreciated that the halfsections' is of the skirt section I are retained against relative axial movement between the head 5 of the skirt section 8 but are permitted to freely expand radially in response to the expander 16.

It is thought that a clear understanding of the construction, utility, and advantages of a piston embodying the features of the present invention wil be had without a more detailed description.

Having described the invention what is claimed as new is:

A piston comprising a disk-like head, a lower cylindrical skirt having a closed upper end, a wrist pin extending diametrically through said skirt for the attachment thereto of a piston rod, means to detachably attach said skirt to said head in spaced relation thereto, an expansible unit intermediate said head and skirt comprising a pair of semi-circular sections slidably fitting edge to edge between said head and the upper tively, and relatively separable, spring means beend of said skirt for expansion radially thereof tween said members for separating the same, and and having the edges thereof keyed together, guide means for said members in the separative expanding means for said. sections comprising movement thereof.

a pair of opposed segmental members fitting JOHN S. BRETZ. 5 against the inner sides of said sections, respec- 

